Lock assemblies suitable for use with powered actuators are known and generally comprise a lock housing with two lock barrels therein. The lock assemblies are configured with one barrel able only to be manually driven by a key and the other barrel able only to be driven by the powered actuator. The lock assemblies are normally installed with the power driven barrel positioned on the outward side of a door and the key driven barrel positioned on the inward side of the door.
A disadvantage of this arrangement is that, if the powered barrel is damaged, for example by vandalism or by unauthorised attempts to open the door, then any authorised person subsequently attempting to open the door will be locked out.
Known lock arrangements of this type are also unsuitable for installation with the key driven barrel on the outside and the powered cylinder on the inside as, in the event of a power or other failure of the actuator, persons can be locked on the inward side of the door (i.e. inside the building).